How to Randomly Choose an Element from an Array that Wasn't Chosen before in JavaScript?

Question

I want to run a function that each time randomly chooses an element from an array that wasn\'t chosen before. And if all elements were chosen, I want to reset the used eleme

Answer 1

You can try something like this:

Idea

• Create a utility function that takes an array and returns you a random value.
• Inside this Array, maintain 2 array, choices and data.
• In every iteration, remove 1 item from data and put it in chosenItems
• Once the length of data reaches 0, set chosenItems or originalArray as data and repeat process.

Benefit of this approach would be,

• You dont need to maintain and pass array variable.
• It can be made generic and used multiple times.

function randomize(arr) {
  let data = [...arr];
  let chosenItems = [];

  function getRandomValue() {
    if (data.length === 0) {
      data = chosenItems;
      chosenItems = [];
    }
    const index = Math.floor(Math.random() * data.length);
    const choice = data.splice(index, 1)[0];

    chosenItems.push(choice);
    return choice;
  }
  
  return {
    randomItem: getRandomValue
  }
}

const dummyData = [ 1,2,3,4,5 ];

const randomizeData = randomize(dummyData);

for (let i = 0; i< 10; i++) {
  console.log(randomizeData.randomItem())
}